Elastic yarn and process of making the same



Dec. 17, 1935. r FQSTER 2,024,156

ELASTIC YARN AND PROCESS OF MAKING THE SAME Filed March 21, 1933 ATTORNEY Patented Dec. 11, 1935 2,024,156

UNITED STATES PATENT OFFICE 2,024,156 I ELASTIC YARN AND PROGESS OF MAKING THE SAME Boutwell H. Foster, Maplewood, N. 3., assignor, by mesne assignments, to United States Rubber Company, New York, N. Y.; a. corporation of New Jersey I Application March 21, 1933, serial No. 061,924 16 Claims. (01.117-35) This invention relates to an elastic yarn consisting of an elastic core and a fibrous covering sheathing said core, and more particularly to a soft, pliable and balanced yarn having a helically wrapped cover comprising loosely aggregated fibres, and to the process of making the same.

It has previously been supposed that the production of elastic yarn having a helical fibrous covering was possible only by the use of hollow spindles through which an elastic core element is drawn under tension while the covering is wrapped around it by the rotating spindle carrying the previously spun yarn, and such has been the universal practice. Moreover, it has been customary to thus apply two such covers successively and in opposite directions in order to produce a balanced yarn, such yarn being relatively hard and stiff, due to the twist present in the covering yarns prior to their incorporation with the elastic core.

A double covered balanced elastic yarn wherein both layers of covering are wrapped around an elastic core in the same direction has been unknown.

All of the elastic yarns of the prior art having helically wrapped coverings are .open to the objections that the inner covering yarns by reason of their compact cylindrical form embed in and tend to cut the material of the core, resulting in undue wear and breakage thereof, and that the elastic .yarns are relatively hard, coarse and inflexible. Further, when the previously known elastic yarns are out or broken, the covering frays or ravels at the cut or broken ends, and the elastic core contracts longitudinally, being no longer held under tension by the thus loosened covering.

An object of my invention is to provide an elastic yarn having a helically wrapped cover comprising loosely aggregated fibers holding an elastic core under tension.

Another object is to provide an improved elastic yarn which is fine, soft to the touch, and'fiexible.

Still another object is to provide an elastic yarn in which the covering grips the elastic core uniformly over the entire area of the core without distortion of the latter.

A further object is to provide anelastic yarn in which the cover will not loosen or move relatively to the core upon repeated stretching.

A still further object is to provide an elastic yarn which will not fray or ravel at out or broken ends.

A still further object is to provide a double cover balanced elastic yarn in which both covers are wrapped around the core in the same direction.

A still further object is to providea process for making the improved yarn.

Other objects will appfiar from the detailed description and drawing, in which latterof one form of machine for carry out the invention;

Figure 2 is a diagrammatic view of a modification;

Figure 3 is a view of an elastic yarn compris- 6 ing an elastic core and a covering of a roving; and

Figure 4 is'a view of an elastic yarn comprising an elastic core, an inner. cover of a roving, and an outer cover of spun yarns.

Broadly the process comprises wrapping or 10 spinning one or more drafted rovings or similar substantially untwisted strands having loosely aggregated fibers helically about an elastic core, such as a rubber core, held under tension and having a twist opposite in direction to that imparted to the roving drafted by the wrapping or spinning process. It further includes a similar process wherein a plurality of rovings are drawn out and spun together helically about such an elastic core. I

In practicing the process, a roving may first be drafted to the desired size on any suitable machine, only a nominal twist being inserted, as in common spinning, to enable the drafted roving to be wound upon a bobbin and to be unwound therefrom. A suitable rubber core may be twisted and tensioned in any desired manner, and the core and the drafted roving may then be fed simultaneously to the feed rolls of a twisting or doubling machine and the roving wrapped helically upon the twisted and tensioned rubber core and the resulting elastic yarn wound up. The twist imparted by the wrapping operation is opposite in direction to the initial twist of the rubber or other elastic core, and since the effect of the wrapping upon the rubber core is to partially untwist it, by an amount equal to the doubling frame twist, it is evident that in order to have some twist remaining in the rubber after the spinning, the initial twist in the rubber, prior to its delivery for wrapping, should exceed numerically the spinning frame twist.

Preferably, however, the final drafting of the roving and the wrapping of the same around the elastic core are carriedout concurrently on a spinning frame. The process may be carried out on any of the common types of commercial spinning machines, such as the ring frame, the throstle or flier frame, and cop frame, and the mule, the choice of the machine to be used depending upon the characteristics of the fibres employed. For example, cotton coverings are most conveniently applied by means of a ring spinning frame.

In Figure 1 there is disclosed diagrammatically one form of machine, viz. a ring spinning frame, for carrying out the process. In the figure, the numeral l designates bobbins filled with rovings, which bobbins are mounted on the creel of the machine. The rovings 2, upon delivery from the B0 bobbins, are passed over the guide 3 and under the guide 4 and thence through a traverse rod 5 and through the successive pairs of drafting rolls 6, l, and 8, by which rolls the rovings are drawn out in the desired ratio. The previously twisted and tensioned rubber core is carried on a spool 9 which may be mounted on the creel of the machine, and the core I is fed from the bobbin through a pigtail guide II and then to the nip of the front draft rolls 8, where it is associated in side by side relation with the drafted roving. The pigtail guide I I is mounted to move in unison with the traverse rod 5. While'the rubber core may be already under the approximate desired tension when wound on the spool 9, it is desirable to have a final adjustment of the core tension in order to produce a balanced yarn, and this adjustment may be obtained, for example, by means of a friction brake controlling the rotation of the core spool 9, this brake consisting of a pulley l2 mounted on the spindle of the bobbin, which pulley is-in frictional engagement with a variably weighted cord [3. Any

other suitable means maybe used for the adjust-v able control of the rotation of the core spool.

Upon emerging from the front draft-rolls 8, the roving and elastic core pass through a pigtail guide l4, thence through the ring traveller l mounted on the ring I6 and on to the bobbin l1 fixed to spindle ll which is rotated by the pulley l8. As before pointed out, the direction of rotation of the bobbin I1 is such as to twist the roving and elastic core ina direction opposite to the original twist of the elastic core, resulting in a partial untwisting of said core. Hence the elastic core is originally given a twist sufficiently in excess of the spinning frame twist, numerically, but opposite in direction thereto, to result in the core in the finished yarn retaining the.

proper amount of twist to balance the yarn. Concurrently with the twisting of the drafted roving about the rubber core thread as the roving and the thread emerge from the front draft rolls, there occurs some longitudinal contraction of the elastic core, since the tension on the elastic yarn, due to the ballooning of the yarn between the pigtail I4 and the ring traveller I5, is less than the tension under which the rubber thread is delivered to the front draft rolls 8. Obviously, the amount of contraction is such that the tension in the yarn becomes equal to the pull arising from the ballooning of the yarn (neglecting frictional effects). Consequently the yarn is wound upon the bobbin ll under this tension, corresponding to an elongation of the fully relaxed yarn equal in general to at least threequarters of the elongation obtained when the yarn is stretched to the limit.

A tensioning device on the spool 9, such as that shown in the drawing, is necessary in order to make any slight adjustments in tension'required to correct for variation in running conditions, and for variations in properties of the materials. Therefore, the data given in the tables herein for the tension of the twisted rubber core and for the number of turns of twist to produce a balanced yarn are approximate and, subject to tolerance.

If it is desired to superpose a second covering of spun yarn upon the firstcovering, this may be accomplished concurrently with the application of the first covering, by mounting a bobbin IQ of suitable spun yarn on the creel of the ma-'' chine, the yarn being led from the bobbin over a guide20 and then down through the pigtail guide II and thence together with the elastic core to be associated with the roving at the front draft rolls 8. The spinning operation is carried out in the same manner as before, and results in a balanced yarn in which the rubber core is 5 twisted in one direction and the two coverings are wrapped in superposed relation around the core in a direction opposite to the twist of the core, with the roving next to the core and completely sheathing the core. The number of 10 wraps of the spun yarn composing the outer cover and of the roving forming the inner cover necessarily are equal, as a consequence of the method of applying the covers, and since the individual turns of the spun yarn are more compact than those of the inner cover, they will be spaced apart longitudinally on the inner covering formed by the roving. The gaps between successive turns of the outer cover may be partially or completely closed up by delivering a plurality of spun yarn ends simultaneously and in parallel to the front draft rolls, where they are associated with the elastic core and the roving.

\ In this manner the soft inner covering of the roving may be completely sheathed bya relatively hard, outer covering, the number of such .spun yarn ends required for this purpose being this figure the numeral 2| designates a spool of previously twisted and tensioned rubber core, the spool being provided with a variablyweighted friction brake 22 for making a final adjustment of the tension of the rubber thread. The rubber thread 23 upon being drawn fromthe spool passes under the guide 24 and then through the feed rolls 25, 26 and 21. The previously drafted roving may be mounted on a bobbin 28 carried on the creel of the machine, and the roving 29 is led from the bobbin and associated with the elastic core just prior to the passage of the latter through the feed rolls 25, 26 and 21. The rubber thread 23 and roving 29 then pass through a pig- 5 tail guide 30 and through the ring traveller II on the ring 32, and are wound upon the spool 33 fixed to spindle 33' which is rotated by the pulley 34. By virtue of the rotation of the spool the roving is helically wrapped around the core. As before, the direction of rotation of the spool 33 is such as to twist the roving and elastic core in a direction opposite to the original twist of the elastic core; and, as in the previous case, the elastic core is originally given such degree of twist as to result in the core in the finished yarn retaining the proper amount of twist to balance the yarn.. A machine of the type shown in Fig. 2 is also suitable for imparting the original tension and twist to the elastic core used. When so employed, the untensioned and untwisted elastic core willbe mounted on the spool 2| and drawn off beneath the guide rod 24 and through the feed rolls 25, 26, and 21, the tension on the core being regulated by the friction brake 22. The tensioned elastic core then passes through the pigtail 20 and the ring traveller II, and is wound on the spool 33, the spindle 33' being rotated in a direction to impart the desired twist to the core. In Fig. 3 there is shown on an enlarged scale a section of elastic yarn made by the process. In this yarn the twisted and tensioned elastic core -is designated by the numeral 35, and the helically wrapped drafted roving is designated by the 76 numeral 38. Due to the loosely aggregated na- 1 ture of the drafted roving and the manner'in which it is applied to the core, the adjacent turns of the roving tend to amalgamate and forma continuous integral cover in which the identity of the individual turns is largely lost, and the fibers bind the rubber core closely. In the finished elastic yarn made by my process, it is practically impossible to unravel the covering at a cut or broken end. Also, by reason of the fact that the fibers of the drafted roving are loosely aggregated, and not twisted into a substantially cylindrical bundle as in the case of a previously spun yarn, the fibers are distributed substantially uniformly over the entire area of the core, so that the gripping action of the roving on the core is very uniform and the cover does not tend to become displaced longitudinally of the core upon repeated stretching.

ANALYSES F COVERED RUBBER THREADS In Fig. 4 there is shown a section of elastic yarn having a double cover, the twisted and tensioned core 35 being covered by the drafted roving 36 constituting the inner cover, and the Your plied yarns 37 being superposed thereon and constituting the outer cover. The elastic yarn shown in Fig. 4 is unique in that the two covers formed by the roving and the spun yarn are put on simultaneously, and the yarn is balanced even'though both covers are wrapped in the same direction. In the following two tables are shown analyses of nine constructions of covered rubber thread made by the process 01 the invention, constructions I to 5 and l to 9 being of yarns having a while in construction 6 a double cover has been applied consisting of an inner cover of a drafted roving and an outer cover of one end of spun yarn.

Table I Sample No.

1. Gauge of bare circular rubber core-re- :l 1

BX m 020' OZ) 013' 01 2. Elongation oi twisted rubber core beiore spinning pp 250% 250% 200% 300% 3. Twist per inch oi rubber core before spmfl "(i-"r t; "6B8" 28 5 28 5 3.5 39 2 39 2 4. Yardage of one poun o are ru r Ycorgg-relaxed d t 2, 500 2, 500 2, 500 5 7 5| 700 5 ar 1' poun o thread relaxod 1, 970 2, 360 2, 170 4, 7 4, 490 0. Elongation-increase over normal len th on stretching to limit (0! covered rub r em) 1 o 1 180 145% 170% 7. Material used in cover Cotton- Cotton Cotton cotton cotton 2 ends 2 ends 1 end 1 end elastic yarn 1.1.15.5 "55"? 13. 4B 20.1R 18. 7B 27. 4B 55. OR l0.In1 rdoinorm e ticyarn, c ese berg core relaxed 32% 22% 21% 25%" e. elongation oi rubber core in normal elastic yarn 10% 61% 66% 42. 5% 11. in one ynrd oi norgnal elastic yarn the Wei 1; n grams 0 a. r ub r 147 098 .093 054 051 0. both rubber and cover 226 192 209 106 103 12. Per cent (by weight; oi rubber core. 51% 44. 5% 51% 47. 2% 4 13. Per cent (by weight oi cover 35% 49% 55. 5% 49% 51 14. Gauge in inches oil normal elastic yarn I I I (product) 2 0748 0258 018' 019' Table II Sample No. 0 7 8 9 1. Gauge of bare circular rubber core-relaxed .013" 010" .010" 00g" 2. Elongation .oi twisted rubber core beiore s p (approximately) 175% 210% 300% I 3. Twist per'inch oi rubber core beiore spinning 39. 2 78. 4 98 97. 6 4. Yardage oi one pound oi bare rubber core-relaxed. 5, 700 10, 200 10, 200 16, 000 5. Yariis ger pound of covered rubber thread- 4,12) 6, 300 11, 900 13, 700

re er 6. Elongation-increase over normal length on stretching to limit (oi covered rubber core) 75% 7. Material used in cover Cotton Cotton Cotton Cotton 1 end 1 end 1 end 4 bank 4 bank 4 bank roving. roving. roving 10. 5 14 12. 5 22. 0 39. 2 35. 0 3. 71. 0L 90.0L 86. 0L 'l 9.

yarn M in h b 35.011. 29. 7B 89.3R 101. SR 1. lyardoinormal cyaru ceso are 0 mm rnlnrnrl 25 ml! 7 d. elongation oi rubber com in normal elastic yarn 44% 55% 73.5% 106% 11. In one yard of normal elastic yarn the weight in 0 grams oil 0. rubber .053 .05 .023 .0132 0. both rubber and cover 110 .072 038 0000 12. Per cent (by weight) 01 rubber core- 48. 2% 30% 60. 5% 43. 6% 13. Per cent (by weight) oi cover. 51. 8% 64% 39. 5% 54. 4% 14. Gauge in inches oi normal elastic yarn (product)-- 0185 I 015 01 010" While any suitable core of elastic material may be used, it is preferred to use a rubber core made directly from rubber latex, and preferably from a rubber latex which has been purified and concentrated. Such rubber direct from latex is grainless and unmilled and has high tearing and tensile strength, good ageing qualities, and thread may be made from it of round cross section. For instance, the rubber core produced by the process described in patent to Hopkinson et al. No. 1,545,257, dated July '7, 1925, may be used. Square and other forms of cut thread may also be used. The rubber may also be compounded with antioxidents to further improve the ageing qualities.

Various fibres may be used in the covering material, such as those of cotton, wool, worsted, spun silk, spun rayon, or any other suitable materials, or combinations of two or more of them.

The process produces a covered elastic yarn having unique and superior qualities. By the use of rovings the fibrous covering on the yarn consists of loosely aggregated substantially parallel fibres wrapped hellcally around the twisted and tensioned elastic core, in place of the usual spun yarns. As a result, the, fibres are spread uniformly over and in contact with the entire area of the core, instead of contacting the core at spaced intervals as in the case of spun yarn coverings, and by reason of this construction, the

cutting action of the inner .cover upon the core is reduced to a minimum and the binding effect of the fibres is greater since it is spread out over the entire area ofthe core. The construction is such that the covering is firmly and permanently bound to and completely sheaths the core; it does not loosen when the yarn is repeatedly stretched and relaxed; and it does not fray or ravel at cut or broken ends,-in fact, it is exceedingly difiicult to unravel the covering at 9.11,

can be made very soft,.fine and fiexlble, and with.

a good handle, and this renders it well adapted for use in knitting.

The rate of production of covered rubber thread made possible by my spinning method is greater than that of previous known methods.

particularly The production of anelastic yarn having a number 's rubber core, and one end of 50/1. cotton for the inner cover, and three ends of /1 cotton for the outer cover, by prior methods, is 12 lbs. per 8'hrs., for two tiers of 48'spindles each, I

with spindle speeds of 9,500 and'6,200 R. P. M. re-

spectively. The production for construction 5,

made azcordlng to my method, with the same size rubber core75s'and one end of 4 hank cottonroving drafted 6.4, which is approximately the same weight of cotton as used in the double covered construction just mentioned, is 25.5 lbs. per 8 hrs. for 96 spindles, with a spindle speed of 5,800 B. P. M. Thus, I may obtain greater production at lower spindle speeds, or I may obtain still greater production at higher spindle speeds. This shows the advantages of the greater covering capacity of cotton in roving form and where the individual fibres are wrapped hellcally the same direction as said roving and covering around a core, as compared with cotton condensed or compact as when a yarn or bundle of fibres is wrapped hellcally around a core.

It will also be seen that by the use of the process, .an inner cover of a roving and an outer cover of spun yarn or yarns can be simultaneously applied in a single twisting operation, and the resulting yarn is a balanced one although both coverings arewrapped on in the same direction, this direction, of course, being opposite to the twist of the elastic core.

'When the rubber core to be covered is quite fine, say as fine as approximately 100s counts, a very small amount of fibre is required to cover the core, and in this case the drafted roving or ribbon of yarn supplied to the spinning mecha nism by the drafting rolls of Fig. 1 should be smaller than any roving that can be successfully handled. Therefore, in covering a fine rubber core in accordance with the disclosure of Fig. 1 hereof, it is desirable that the drafting rolls 6, l, and 8 draft the roving sufficiently to form what may be termed a very small ribbon of straight fibres having no appreciable tensile strength and which is incapable 01! supporting an appreciable length of its own weight.

around the rubber core as the fibers of this rib- 3 bon leave the 'nip of the rolls. In this way an elastic yarn may be produ:ed which is smaller than any elastic yarn it has been possible to produce heretofore, and which feels and handles very much like ordinary inelastic yarn.

In order to carryout the process, no special machinery is required, as it may be carried out by the use of ordinary textile yarn machinery without any modification other than the'installation of friction devices on the creel of the machine to regulate the tension of the rubber core.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A balanced elastic yarn comprising a tensioned and twisted elastic core, and a cover comprising successive layers respectivlyof loosely aggregated fibers and of spun fibers both wrapped hellcally upon and around said core in a direction reverse to the twist of the core and holding said core under tension.

2. An elastic yarn comprising a tensioned and twisted rubber core, a wrapping of loosely aggregatedfibersextending hellcally around said core in. a direction reverse to the twist of the core and holding the latter under-tension, and a 55 said fibers.

4. an elastic yarn comprising a twisted and tensioned core of unmilled grainless rubber, a

roving wrapped hellcally around said core in a 0 direction reverse to the twist of said core and holding the latter under tension, and a plurality of spun yarns, wrapped hellcally around and in the latter.

5. An elastic yarn comprising atwisted and tensioned round core of unmilled grainless rub.- ber, a roving wrapped helically around said core in a direction reverse to the twist of said core and holding the latter under tension, and a plurality of spun yarns wrapped helically around and in the same direction as said roving and covering the latter.

6. A process for making elastic yarn comprising associating a twisted and substantially elongated tensioned elastic core, a strand of loosely aggregated fibers, and a strand of spun yarn in side by side relation, and twisting them in a direction reverse to the twist of said core.

7. A process for making elastic yarn comprising associating a twisted and substantially elongated tensioned elastic core, a roving, and a spun yarn in side by side relation, and simultaneously partly untwisting the core and twisting together the core, roving and spun yarn in a direction reverse to the twist of the core, whereby the roving and spun yarn are wrapped around the core in superposed relation.

8. A process for making elastic yarn comprising simultaneously drafting a roving and associating with the drafted roving a twisted and substantially elongated elastic core under regulated tension, and twisting together the core and roving as the latter is drafted in a direction reverse to the twist of the core, whereby a helical covering of a thin ribbon of substantially parallel fibers is formed on the core.

9. A process for making elastic yarn comprising associating in side by side relation and advancing in the direction of their length a ribbon of loosely aggregated substantially parallel fibers and a tensioned and substantially elongated elastic core element twisted in excess of its twist in the finished yarn, and twisting them in a direction reverse to the twist of said core, whereby in the finished yarn the cover and core are balanced in torque and the yarn when relaxed or at rest is substantially kinkless.

10. A process for making elastic yarn comprising simultaneously drafting a roving into a thin ribbon of substantially parallel fibers which is incapable of supporting an appreciable length of its own weight and wrapping this fine ribbon directly about a tensioned and twisted elastic core at the nip of the final drafting point and in a direction reverse to the twist of the core, whereby a covering of a thin ribbon of substantially parallel fibers is formed on the core to hold the core stretched and twisted.

11. A process for making elastic yarn comprising associating a thin ribbon of substantially straight drafted fibers and -a twisted and stretched rubber core in side-by-side relation, and simultaneously twisting together the two to wrap the ribbon about the core and winding up the thus produced covered yarn, the direction of twist being reversed to the twist of the core 5 and being such that thetwist that remains in the core will balance the twist of the ribbon cover.

12. An elastic yarn comprising a stretched and twisted elastic core, and a cover formed of a thin drafted ribbon of substantially parallel fibers wrapped helically upon and around said core in a direction reverse to the twist of the core and the ribbon cover holds the core stretched.

13. An elastic yarn comprising a stretched and twisted elastic core, and a cover comprising a thin drafted ribbon of substantially parallel fibers wrapped helically upon and around said core in a direction reverse to the twist of the core, whereby the twist of one balances the other and the ribbon cover holds the core stretched.

14. An elastic yarn comprising a tensioned and twisted elastic core and loosely aggregated substantially parallel fibers wrapped helically upon and around said core to form a cover engaging the core at all points of its surface without distortion as of the surface and holding said core stretched, the direction of wrap of said fibers being reverse to the twist of the core.

15. An elastic yarn capable of being knitted, comprising a stretched elastic core of rubber twisted as an entirety in one direction to main- 1 tain it under torque and unbalanced from said twist, and a fibrous covering helically wrapped in the opposite direction in direct frictional contact with the core to provide a covering that holds the core in a stretched condition, and the twist of the core being just suflicient to balance the opposite helical twist of the cover, whereby an accurately balanced elastic'yarn which can be knitted in a knitting machine without kinking 40 is produced.

16. An elastic yarn comprising a stretched elastic core of rubber twisted as an entirety in one direction only and having an inherent tendency to untwist, and a fibrous covering helically wrapped upon and around said core in the opposite direction in direct frictional contact with the stretched core, the tendency of the core to untwist when the yarn is in a relaxed condition being just suflicient to balance the opposite spiral wind of the cover and opposed solely by the frictional engagement of the covering with the core and said frictional engagement being sufiicient to hold the core in said stretched and twisted condition, whereby a balanced elastic yarn that is free from tendencies to kink is produced.

BOUTWELL H. FOBIER.

CERTIFICATE OF CORRECTION.

Patent No. 2,024,156. 4 December 17," 1935.

BOU'I'WELL H. FOSTER.

It is hereby Certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 13, claim 12., strike out the words "the ribbon cover holds" and insert instead tight enough to hold; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 18th day of February, A. D. 1936.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

